Synthesis and characterization of new soluble polyamides derived from 2,6-bis(4-aminophenyl)-3,5-dimethyltetrahydro-4H-pyran-4-one

A new oxypyrone diamine, 2,6-bis(4-aminophenyl)-3,5-dimethyltetrahydro-4H-p yran-4-one (DAPP), was prepared from 4-nitrobenzaldehyde and 3-oxa-n-pentan e in a two-step reaction with a high yield and a high purity. Aromatic poly amides were obtained from this novel condensation monomer and several diaci d chlorides through the conventional low-temperature solution method in iv, N-dimethylacetamide. Polycondensation results were consistent with a high r eactivity for DAPP because high yields and high molecular weight polyamides were obtained with inherent viscosities up to 1.8 dL/g, The reactivity of DAPP was also estimated with theoretical calculations from computer program s for molecular simulation, with orbital and charge factors considered. The polymers showed improved solubility in organic solvents, relative to conve ntional wholly aromatic polyamides, and high glass-transition temperatures (from differential scanning calorimetry) over 270 degreesC. However, the th ermal resistance, as estimated by thermogravimetric analysis, was lower tha n that of conventional aromatic polyamides; nevertheless, decomposition tem peratures well beyond 300 degreesC were observed in nitrogen and air. (C) 2 001 John Wiley & Sons, Inc.